Test head positioner system

ABSTRACT

A manipulator system comprising a column unit and a carriage supported by the column unit and configured to move along a desired axis of translation. A marker is provided on the column unit along the axis of translation. A sensor is associated with the carriage and configured to sense a position along the marker. A position display unit is configured to receive a position signal from the sensor and display a current position of the carriage along the axis of translation. In another aspect, the column unit defines at least one slot. A lock assembly is attached to the carriage and includes a tang axially moveable between an unlocked position wherein the tang is disengaged from the at least one slot and a locked position wherein the tang is engaged in the at least one slot.

This application is a divisional of U.S. patent application Ser. No.12/405,547, filed Mar. 17, 2009, which is the nonprovisional of U.S.Patent Application No. 61/037,065, filed Mar. 17, 2008, both which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of art of test headpositioners for automatic integrated circuit (IC) testing equipment.

BACKGROUND OF THE INVENTION

Automatic test equipment (ATE) for integrated circuits (ICs) has beendeveloped to facilitate electrical testing of IC's at selected stages ofthe IC manufacturing process. Such ATE often includes a test head whichmust be manipulated into a docked position with a testing peripheralusing a test head positioner (or manipulator). Test head positioners aregenerally described, for example, in U.S. Pat. Nos. 6,911,816,6,888,343, 5,608,334, 5,450,766, 5,030,869, 4,893,074, 4,715,574,4,705,447 and 4,527,942, WIPO publications WO 05015245A2 and WO04031782A1, and U.S. patent application Ser. No. 10/955,441. All of theforegoing are incorporated by reference in their entirety for theirteachings in the field of test head positioners for automatic testequipment for integrated circuits or other electronic devices.

Briefly, a conventional automatic testing system generally includes aperipheral apparatus for precisely placing and constraining the ICdevice under test (DUT) in a fixed position test site. Also included isa moveable test head for testing the DUT. The peripheral apparatus may,for example, be a wafer prober for testing devices before they areseparated from a silicon wafer or a package handler for positioning andtesting packaged devices. In practice, the test head is translatedand/or rotated about one or more axes and brought into the vicinity ofthe DUT test site included in the peripheral apparatus. Prior todocking, the mating connectors of the test head and the DUT test siteare precisely aligned to avoid damaging any of the fragile electricaland mechanical components. Once docked, test electronics of the testhead transmit signals through various contacts of the DUT and executeparticular test procedures within the DUT. In the course of testing, thetest head receives output signals from the DUT, which are indicative ofits electrical characteristics.

In order to precisely mate the test head with the peripheral apparatus,the test head is optionally capable of movement with all six degrees ofspatial freedom. To facilitate such motion, a test head positionersystem is commonly employed to precisely position the test head withrespect to the peripheral. The test head positioner system may also bereferred to in the art as a test head positioner or a test headmanipulator.

Referring now to the exemplary test head positioner described in U.S.Pat. No. 6,888,343, the test head 502 is coupled to main arm 511, andmain arm 511 is slideably coupled to linear guide rail 510 that extendsvertically along the length of column 545, as best shown in FIGS. 5A and5B. A motor 2416 may be adapted to translate main arm 511 (and test head502) vertically along linear guide rail 510. A counter weight assemblybiases the weight of main arm 511 (and test head 502) in a substantiallyfixed vertical position upon disengagement of the motor. As best shownin FIGS. 23 and 24, motor 2416 is mounted to frame 2422 of column 545,and is indirectly connected to pulley 2421 by timing belt 2420. Pulley2421 is mounted to pulley 2406 by fasteners 2407 (shown in FIG. 23, butnot numbered), such that pulleys 2421 and 2406 rotate simultaneously. Acable 2410 is positioned about pulley 2421. One end of cable 2410 iscoupled to mount 736 of main arm 511 and the opposing end of cable 2410is coupled to a counter balance 2413. In operation, if clutch 2426 ofmotor 2416 is engaged, the motor 2416 rotates pulleys 2406 and 2421,thereby translating the end of cable 2410 that is connected to mount 736along the Y-axis. Thus, the cable 2410 translates the mount 736 of mainarm 511, along with test head 502, in a vertical direction. Once clutch2426 of motor 2416 is disengaged, the counterbalance 2413 suspends mount736 and test head 502, in a substantially fixed vertical position.Furthermore, with clutch 2426 of motor 2416 disengaged, test head 502 isin a substantially weightless condition and may be readily movedvertically with a relatively small externally (manually) applied force.This is known as compliance and it enables an operator to manuallyposition the test head or a docking apparatus to maneuver the test headinto or out of its docked position with a peripheral.

Further, the exemplary test head positioners disclosed in WO 05015245A2,and WO 04031782A1, and U.S. Pat. No. 4,705,447 both support a test headin a substantially-weightless, compliant condition using a pneumaticapparatus rather than counter weights. In WO 05015245A2 and WO04031782A1 a pneumatic controller is provided which, in addition toproviding compliance, automates vertical translation of the test head.

The aforementioned test head positioner systems may be sufficient;nevertheless, there continues to be a need to further improve verticalsupport systems for test heads, in the interest of weight, efficiency,simplicity and cost.

SUMMARY OF THE INVENTION

The present invention relates to a test head manipulator system whichgenerally includes a column unit, a vertical carriage, a cradle, an armassembly including a roll gear box, and a base unit. The cradle isconfigured to hold a test head at two points, which define an axis thatpasses approximately through the test head's center of gravity. The testhead may compliantly pivot about this axis.

The cradle is held by a roll gear box assembly which includes a handwheel whereby rotating hand wheel drives a worm gear mechanism.Optionally, a motor may be provided to drive the worm gear mechanism.This worm gear mechanism turns a coupling to which the cradle isattached. Thus, rotating hand wheel causes rotation of the cradle andthe test head about its roll axis. In an exemplary embodiment, the rollgear box provides plus/minus approximately 95 degrees of roll motion,which enables the test head to be moved to, and placed in, any dut up,dut down, dut vertical, or intermediate angular position. Rollcompliance for docking may be provided by a number of known techniques,including the incorporation of Bellville washers in a manner to allowresilient axial motion of the worm gear.

The arm assembly generally includes a main arm plate with a proximal endof an upper arm assembly pivotably attached thereto by means of journalsand bearings that are situated to define a vertical pivot axis. The rollgear box assembly is pivotally coupled to a distal end of the upper armassembly, also with appropriate journals and bearings to define a secondvertical pivot axis. The main arm plate is slidlingly attached to thevertical carriage by means of horizontal rails and linear bearings.Horizontal side-to-side motion is provided by moving main arm platealong the horizontal rails and the associated bearings.

The combination of the two vertical pivot axes and the horizontal linearmotion provides low friction motion of cradle (and the attached testhead) throughout a horizontal plane with three degrees of freedom (X, Z,and rotation about Y).

The column unit includes two linear rails which extend vertically fromapproximately the bottom to the top thereof. The vertical carriage iscoupled to the rails with appropriate linear bearings or the like.Straps connect to the vertical carriage and lead upwards to and overdirection reversing pulleys located at the top of the column and thencedownwards to a counterweight assembly. The counterweight assembly servesto balance the load coupled to the vertical carriage, placing the systemin essentially a state of equilibrium.

In one aspect, the invention may provide a manipulator system comprisinga column unit and a carriage supported by the column unit and configuredto move along a desired axis of translation. A marker is provided on thecolumn unit along the axis of translation. A sensor is associated withthe carriage and configured to sense a position along the marker. Aposition display unit is configured to receive a position signal fromthe sensor and display a current position of the carriage along the axisof translation.

In another aspect, the invention may provide a manipulator systemcomprising a column unit defining at least one slot and a carriagesupported by the column unit and configured to move along a desired axisof translation. A lock assembly is attached to the carriage. The lockassembly includes a tang axially moveable between an unlocked positionwherein the tang is disengaged from the at least one slot and a lockedposition wherein the tang is engaged in the at least one slot.

-   -   In another aspect, the invention may provide a manipulator for        positioning a load comprising a base unit including a toothed        rail; and a column configured to support the load. The column is        moveably supported on the base unit and includes a rotative        actuator that drives a gear along the toothed rail to effect        movement along the base unit.    -   In yet another aspect, the invention may provide a lock for an        arm that pivots about an axle. The lock comprises a clamp        extending about a portion of the axle and including at least one        moveable portion which defines a clamping force based on its        position. An actuating member is configured to engage the clamp        moveable portion and is moveable between at least two positions        to define at least two different clamping forces on the axle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingare not to scale. On the contrary, the dimensions of the variousfeatures may be arbitrarily expanded or reduced for clarity. Included inthe drawing are the following figures:

FIG. 1 is a perspective view of an exemplary test head manipulatorsystem;

FIG. 1A is a coordinate system related to the system of FIG. 1.

FIG. 2 is an exploded perspective view of the test head manipulatorsystem of FIG. 1;

FIG. 3 is an exploded perspective view of an exemplary base assembly ofthe test head manipulator system of FIG. 1;

FIG. 4 is an assembled perspective view of the base assembly of FIG. 3;

FIG. 5 is an expanded perspective view of a portion of the base assemblyof FIG. 3;

FIG. 6 is a perspective view of the base assembly similar to FIG. 3illustrating relative positioning of the column unit with respectthereto;

FIG. 7 is a front, right perspective view of an exemplary column unit;

FIG. 8 is a front, left perspective view of the column unit of FIG. 7;

FIG. 9 is a rear perspective view of the column unit of FIG. 7 with theaccess door in a closed position;

FIG. 10 is a rear perspective view of the column unit of FIG. 7 with theaccess door removed and the counterweight assembly and straps omittedfor clarity;

FIG. 11 is a bottom, rear perspective view of the column unit similar toFIG. 10;

FIG. 12 is a expanded left, rear perspective view of a portion of thecolumn unit;

FIG. 13 is a expanded bottom, rear perspective view of a portion of thecolumn unit;

FIG. 14 is a perspective view of an exemplary counterweight assembly;

FIG. 15 is a perspective view of an exemplary weight plate;

FIG. 16 is a rear perspective view similar to FIG. 10 but showing thecounterweight assembly and straps;

FIG. 17 is a rear perspective view similar to FIG. 11 but showing thecounterweight assembly and straps;

FIG. 18 is an expanded rear perspective view similar to FIG. 13 butshowing the counterweight assembly and straps;

FIG. 19 is a front perspective view of an exemplary vertical carriage;

FIG. 20 is a rear perspective view of the vertical carriage of FIG. 19;

FIG. 21 is a cross-sectional view along the line 21-21 in FIG. 19;

FIG. 22 is an exploded perspective view of an exemplary safety servicelock;

FIGS. 23 and 24 are front and rear partial perspective viewsillustrating the safety service lock in an unlocked condition;

FIGS. 25 and 26 are front and rear partial perspective viewsillustrating the safety service lock in a locked condition;

FIG. 27 is an exploded perspective view of an exemplary arm assembly;

FIG. 28 is an assembled perspective view of the arm assembly of FIG. 27;

FIG. 29 is a front perspective view of an exemplary main arm plate;

FIG. 30 is a rear perspective view of the main arm plate of FIG. 29;

FIG. 31 is a perspective view of an exemplary upper arm assembly;

FIG. 32 is a partially exploded view of the upper arm assembly of FIG.31;

FIG. 33 is a top perspective view of the upper arm assembly of FIG. 31with its cover removed;

FIG. 34 is an expanded view of a portion of the upper arm assembly asshown in FIG. 33;

FIG. 35 is an exploded view of an exemplary roll gear box assembly;

FIG. 36 is an assembled, partially cut away, rear perspective view ofthe roll gear box assembly of FIG. 35 with a rear cover removed;

FIG. 37 is a perspective view of a manipulator system according to analternative embodiment of the present invention;

FIG. 38 is an expanded perspective view of a portion of the manipulatorsystem of FIG. 37;

FIG. 39 is an expanded rear perspective view of a portion of themanipulator system of FIG. 37 with the rear access door removed;

FIG. 40 is a schematic illustration of the cable support apparatus ofthe manipulator system of FIG. 37; and

FIG. 41 is a schematic illustration of the manipulator system of FIG.37.

DETAILED DESCRIPTION OF THE INVENTION

The invention will next be illustrated with reference to the figures.Such figures are intended to be illustrative rather than limiting andare included herewith to facilitate explanation of the presentinvention. The figures are not necessarily to scale, and are notintended to serve as engineering drawings.

To be consistent with descriptions of prior art test head positionersystems, a Cartesian coordinate system illustrated in FIG. 1A is used inwhich a vertical axis (otherwise referred to as a Y-axis) is denoted byaxis 1006, a horizontal axis (otherwise referred to as an X-axis,side-to-side axis or left-right axis) is denoted by axis 1002, andanother horizontal axis (otherwise referred to as a Z-axis or in-outaxis) is denoted by axis 1004.

Test head manipulator system 10, which is a first embodiment of thepresent invention, will be described with reference to FIGS. 1-36.Referring to FIGS. 1 and 2, manipulator system 10 generally includescolumn unit 1000, vertical carriage 2000, cradle 3000, arm assembly5000, roll gear box 5800, and base unit 6000. Not shown is the mainframecabinet of the automatic testing equipment (ATE), the test head, and thecable, which connects the test head to the mainframe cabinet. The cablemay contain various equipment, for example, electrical wiring thatconnects signals, power supplies, and grounds between the test head andmainframe cabinet, fiber optic signal connections, and flexible ductingfor air or other gaseous coolants and/or flexible hoses and/or tubingfor liquid coolants for cooling internal components, for example,densely packed very high-speed, precision circuitry.

Cradle 3000 holds a test head at two points 4950, which define an axisthat passes approximately through the test head's center of gravity. Thetest head may compliantly pivot about this axis. Other cradles and testhead holding mechanisms, providing further capabilities and more degreesof motion freedom are known in the art and may be substituted asappropriate for specific applications.

As shown in FIGS. 1 and 2, cradle 3000 is held by roll gear box assembly5800, which includes hand wheel 5862. Rotating hand wheel 5862 drives aworm gear mechanism, which is internal to gear box assembly 5800. Thisworm gear mechanism turns coupling 5832 to which cradle 3000 isattached. Thus, rotating hand wheel 5862 causes rotation of cradle 3000and the test head about its roll axis. In an exemplary embodiment, rollgear box 5800 provides plus/minus approximately 95 degrees of rollmotion, which enables the test head to be moved to, and placed in, anydut up, dut down, dut vertical, or intermediate angular position. Rollcompliance for docking may be provided by a number of known techniques,including the incorporation of Bellville washers in a manner to allowresilient axial motion of the worm gear. Optionally, a motor may beprovided to drive the worm gear.

Arm assembly 5000 generally includes main arm plate 5100 with a proximalend of upper arm 5300 pivotably attached thereto by means of journalsand bearings that are situated to define a vertical pivot axis. Rollgear box assembly 5800 is pivotally coupled to a distal end of upper arm5300, also with appropriate journals and bearings to define a secondvertical pivot axis. Thus, roll gear box assembly 5800 forms a lowerarm.

Main arm plate 5100 is slidlingly attached to vertical carriage 2000 bymeans of horizontal rails 2150 and linear bearings 5150. Horizontalside-to-side motion is provided by moving main arm plate 5100 alonghorizontal rails 2150 and the associated bearings 5150.

The combination of the two vertical pivot axes and the horizontal linearmotion provides low friction motion of cradle 3000 (and the attachedtest head) throughout a horizontal plane with three degrees of freedom(X, Z, and rotation about Y).

Column unit 1000 includes two linear rails 1150 which extend verticallyfrom approximately the bottom to the top thereof. Vertical carriage 2000is coupled to rails 1150 with appropriate linear bearings or the like.Straps 1300 connect to vertical carriage 2000 and lead upwards to andover direction reversing pulleys (not visible) located at the top ofcolumn 1100 and thence downwards to support counterweights (not visible)also located inside column 1100. The counterweights serve to balance theload coupled to vertical carriage 2000, placing the system inessentially a state of equilibrium. As described by Smith in theaforementioned U.S. Pat. No. 4,527,942, the load is thus in asubstantially weightless condition and may be moved upwards or downwardswith a relatively small amount of force. As suggested in U.S. Pat. No.7,245,118, a relatively small motor may be appropriately coupled to thesystem and used to drive the load vertically. Further, as also suggestedin U.S. Pat. No. 7,245,118, the motor may be clutched to enable anexternal force to easily move the load vertically when appropriate.Thus, the load may be either driven by the motor or compliantly moved byan external force.

Base unit 6000 includes horizontally oriented base plate 6050. Linearrails 6300 are provided on base plate 6050. Linear bearings or the likecouple to the bottom of column 1000 to linear rails 6300 such thatcolumn 1000 is readily linearly moveable in a plane parallel to thefloor. This linear motion defines the in-out axis. Column unit 1000 isthereby provided with in-out linear motion relative to base unit 6000.As will be described, a suitable actuator mechanism may be included toprovide powered in-out motion.

Referring to FIG. 1, the X-axis 1002 is oriented in a horizontal planewhich is parallel with the floor, base plate 6050 and horizontal linearrails 2150 such that horizontal side-to-side motion is parallel withX-axis 1002. Z-axis 1004 is also in a horizontal plane, which isparallel with the floor and base plate 6050, and also parallel withlinear rails 6300 located on base plate 6050 such that in-out motion isparallel with Z-axis 1004. Y-axis 1006 is vertical and parallel withlinear rails 1150 such that up-down motion is parallel with Y-axis 1006.X-axis 1002, Y-axis 1006 and Z-axis 1004 are all mutually orthogonal.

Referring to FIGS. 3-6, base assembly 6000 will be described in moredetail. Base assembly 6000 supports and provides in-out motion forcolumn unit 1000. Column unit 1000 includes four linear bearings 1110a,b,c,d on its bottom surface (see FIG. 11). Linear bearings 1110 a,1110 b and 1110 c, 1110 d are configured to engage linear rails 6300 aand 6300 b, respectively, which are mounted parallel to one another onbase plate 6050. Thus, column unit 1000 may move horizontally along anaxis defined by linear rails 6300 a and 6300 b. Linear bearings 1110a,b,c,d are desirably attached so as to be in precise engagement withlinear rails 6300 a,b such that column unit 1000 may be readily movedalong a linear in-out axis with very low friction. Motion-limiting stopblocks 6013 are fixed to the front and rear of base plate 6050 and incooperation with stop units 1113 and 1114 attached to the underside ofcolumn unit 1000 are provided to stop and constrain forward and rearwardmotion respectively of column unit 1000 as described in more detailbelow.

Base plate 6050 is preferably manufactured from steel for strength andminimal flexing as the load is moved from one position to another. Othermaterials, including metallic and non-metallic materials, may also beutilized. Base plate 6050 is supported on a framework 6100 which may bemade from steel or other materials. As shown in FIG. 3, machined area6110 may be provided along each side of the framework 6100 for preciselyattaching base plate 6050 and rails 6300 a,b. As shown in FIG. 5, wiringchannel 6350 may be provided along the upper surface of base plate 6050to contain electrical wiring serving the optional motors, clutches andthe like.

A plurality of caster wheels 6070 are attached to framework 6100. In theillustrated embodiment, a caster wheel 6070 is attached in proximity toeach of its corners. A different number and arrangement of caster wheels6070 may alternatively be utilized. Caster wheels 6070 may be of thefixed or swiveling type according to application requirements. Othertypes of wheels may also be utilized. Also attached to framework 6100are a number of extension legs with support pads 6080 to providestability as the test head is moved throughout its motion envelope. Theillustrated support pads 6080 are of the conventional type, having around flat surface, which faces downwards, and a threaded portion, whichextends upwards and engages an appropriately threaded hole in the memberto which it is attached. Prior to use of manipulator system 10, levelingsupport pads 6080 are desirably rotated so that their flat surfaces arein contact with the floor and caster wheels 6070 are positioned slightlyabove the floor. Support pads 6080 may be adjusted in order to levelbase assembly 6000 and to place column unit 1000 in a desirably verticalposition. Manipulator system 10 may be moved from one location toanother across a reasonably level floor by screwing all leveling supportpads 6080 inwards so that they are clear of the floor. With coasterwheels 6080 in contact with the floor, manipulator system 10 may bereadily rolled to a new location.

Toothed rail 6200 is provided to facilitate in-out (forward-reverse)motion for manipulator system 10. Toothed rail 6200 is positionedbetween linear rails 6300 a,b and extends parallel thereto. The teeth6210 of toothed rail 6200 (see FIG. 5) are configured to engage motordriven drive gear 1115 positioned on the bottom of column unit 1000 (seeFIG. 11). Horizontal drive motor 1130 (see FIG. 10) controllably rotatesdrive gear 1115 clockwise or counterclockwise such that drive gear 1115engages teeth 6210 and moves column unit 1000 in or out relative to baseplate 6050. With the low-friction interface between linear bearings 1110a,b,c,d and linear rails 6300 a,b, significant motor torque is notrequired to move column unit 1000 in or out. Additionally, horizontaldrive motor 1130 may be provided with a clutch mechanism which can bedisengaged to allow a user to manually move column unit 1000 in or out.Horizontal drive motor 1130 preferably locks column unit 1000 relativeto base assembly 6000, however, other lock mechanisms may also beprovided.

Column unit 1000 will be described in more detail with reference toFIGS. 7-18. In these figures, for simplicity, column unit 1000 isgenerally illustrated with main arm assembly 500, roll gear box 580,cradle 300, and base unit 600 omitted therefrom.

Referring to FIGS. 7-11, column unit 1000 includes column body 1010,which provides a vertical support structure as well as an enclosure unitand mounting structure for various apparatus. In the present embodiment,column body 1010 is substantially U-shaped in cross section andfabricated of a suitable material, such as steel, in appropriatedimensions to support the desired load. The U-shaped cross sectionprovides a structure with three contiguous closed sides and asubstantially open back 1145. Rear access door 1190 is supported byhinges 1191 and is pivotal to a closed position as shown in FIG. 9 tosubstantially close column body 1010. Catches 1192 are preferablyprovided to maintain rear access door 1190 in the closed position.Catches 1192 can have various configurations, for example, mechanical ormagnetic. As shown in FIG. 11, vertical supports 1155 and horizontalsupports 1156 may be provided within column body 1010 for additionalsupport.

Referring to FIGS. 7 and 8, one or both of the sides of column body 1010may include a handle 1118 or the like to facilitate manual movement ofthe manipulator system 10. The front side of column body 1010 includespulley opening 1020 through which pulleys 1120 extend. Cover 1160 ispositioned over pulley opening 1020 to enclose pulleys 1120, butincludes an open bottom such that straps 1300 (not shown in FIGS. 7 and8) passing over pulleys 1120 may extend from column unit 1000 and attachto vertical carriage 2000, as shown in FIG. 1. Vertical linear rails1150 extend along each side of the front side of column body 1010 andare configured to engage linear bearings 2115 on vertical carriage 2000,as described hereinafter. Magnetic tape 1140 extends parallel to one ofthe vertical linear rails 1150 and is used with a height sensor, asdescribed below. One or more slots 1135 may be provided through thefront surface of column body 1010 and are configured to receive thelatch of a service lock, as described hereinafter.

Top plate 1162 is fitted to the top of column body 1010 and attachedthereto with screws or other means. Top plate 1162 includes a pluralityof openings with respective covers 1165, 1166, 1167 and 1170 positionedthereover. The opening covered by cover 1170 is provided for optionalequipment, for example, an optional cable handling apparatus. Covers1165, 1166, and 1167 are each a support cover configured to support oneor more pulleys 1120, 1123, 1124. Referring to FIGS. 11-13, cover 1165includes a pair of support blocks 1175 depending therefrom andconfigured to support a pulley shaft (not shown) that supports pulley1123. This shaft also supports a second drive pulley 1188, as describedbelow. Cover 1166 includes a pair of support blocks 1176 dependingtherefrom and configured to support a pulley shaft (not shown) thatsupports pulley 1124. Cover 1167 includes four support blocks 1177depending therefrom and configured to support a pulley shaft (not shown)that supports pulleys 1120. Various configurations of covers and supportblocks may be utilized.

Referring to FIGS. 1 and 11-18, pulleys 1120, 1123 and 1124 areconfigured to support straps 1300 extending between vertical carriage2000 and counterweight assembly 1500. As shown in FIG. 14, counterweightassembly 1500 includes bottom plate 1510 which is attached to top plate1520 by a plurality of vertical supports 1525. A desired number ofweight plates 1530, as shown in FIG. 15, are supported between bottomand top plates 1510, 1520. In the illustrated embodiment, weight plates1530 are provided in two stacks 1530 a and 1530 b. The outside edge ofeach weight plate 1530 includes a pair of notches 1532 to accommodatethe vertical supports 1525. Each weight plate 1530 also includes a pairof rod holes 1534 for passage of a securing rod (not shown) extendingbetween bottom and top plates 1510, 1520. The number of weight plates1530 positioned within the counterweight assembly 1500 will varyaccording to the actual load.

As shown in FIGS. 16 and 17, counterweight assembly 1500 is sized to fitwithin column body 1010 and to travel up and down therein. To guidemovement of counterweight assembly 1500, a pair of guide blocks 1540 areprovided on top plate 1520. Each guide block 1540 includes a pair offront and rear guide rollers 1542 (only rear rollers 1542 shown) and apair of side rollers 1544. Rollers 1542 and 1544 are configured toengage and roll along respective structures (e.g. vertical supports1155) within column body 1010. Each guide block 1540 also includes apair of elastic bumpers 1546 which cushion counterweight assembly 1500in the event it travels to the upper limit of its range of motion.Similar elastic bumpers 1516 depend from bottom plate 1510 and cushioncounterweight assembly 1500 in the event it travels to the lower limitof its range of motion.

Three strap clamps 1550 are also provided on top plate 1520. Each strapclamp 1550 is configured to engage an end of a respective strap 1300 andconnect such to counterweight assembly 1300. Referring to FIGS. 16-18,each strap 1300 extends from a respective strap clamp 1550 and over apair of pulleys 1123 and 1120; 1124 and 1120 or over a single pulley1120 and out of pulley opening 1020. Referring again to FIG. 1, eachstrap 1300 extends from pulley opening 1020 and is connected to verticalcarriage 2000. With straps 1300 extending between vertical carriage 2000and counterweight assembly 1500, the correct number of weight plates1530 can be added to counterweight assembly 1500 to counterbalance theload to provide vertical compliance. Strap clamps 1550 and pulleys 1120,1123, 1124 are preferably positioned to balance the total load, i.e.test head load, arm assembly load and counterweight load, between thestraps 1300. By evenly distributing the total load, each strap 1300 onlyhas to support ⅓ of the total load.

Referring to FIGS. 19-20, vertical carriage 2000 includes linearbearings 2115 a,b,c and d. Linear bearings 2115 a and b are arranged soas to engage one of the linear rails 1150 and linear bearings 2115 c andd are arranged so as to engage the other linear rail 1150 such thatvertical carriage 2000 may translate vertically with very littlefriction along a vertical axis defined by linear rails 1150. Verticalcarriage 2000 includes a plurality of anchor plates 2310 configured toattach the ends of straps 1300 to vertical carriage 2000. Guide bracket2320 may be provided to guide straps 1300 and maintain their orientationwhile alignment bracket 2350 may be provided to align straps 1300 awayfrom and parallel with the rear surface of vertical carriage 2000,parallel with column unit 1000, and tangent to the circumference ofpulleys 1120.

Referring again to FIGS. 11-13, driven vertical motion of verticalcarriage 2000 will be explained. Motor mount 1181 is supported by one ofsupport blocks 1175 and is configured to support vertical drive motor1180 adjacent to pulley 1123. Vertical drive motor 1180 is configured tocontrollably drive a first drive pulley 1184. A clutch 1182 may bepositioned between vertical drive motor 1180 and first drive pulley 1184to allow first drive pulley 1182 to be disengaged from vertical drivemotor 1180, for example, when manual vertical control is desired. Drivebelt 1186 extends between first drive pulley 1184 and second drivepulley 1188. Second pulley 1188 and strap pulley 1123 are fixed to acommon shaft. Thus, when first drive pulley 1184 is engaged withvertical drive motor 1180, the rotational output of vertical drive motor1180 is transferred via drive belt 1186 to second drive pulley 1188,causing strap pulley 1123 to turn. Friction between strap 1300 andpulley 1123 causes the straps 1300 to move, causing the load to move upor down. Because the load is counterbalanced, in equilibrium, and in anessentially weightless state, little power is required. Vertical drivemotor 1180 is geared down appropriately and pulleys 1184 and 1188 aresized appropriately to provide a desired speed. When it is desired tomove the load manually or by some other external force, clutch 1182 maybe disengaged so that the external force does not have to overcomeback-driving the reduction gear mechanism.

Referring again to FIGS. 19 and 20, additional features of verticalcarriage 2000 will be described. Vertical position display 2500 isprovided on the front face of vertical carriage 2000. In the preferredembodiment, vertical position display 2500 is a battery operated unitthat provides a digital readout of the present vertical position ofvertical carriage 2000. Other types of displays, including mechanicaldisplays, may also be utilized. In the present embodiment, magneticsensor 2550 is electrically connected with vertical position display2500 via wires 2551 (only a portion shown in FIG. 20) or any othertransmission means, including wireless transmissions. Magnetic sensor2550 is aligned with magnetic tape 1140 extending vertically alongcolumn unit 1000 as described above. As magnetic sensor 2550 is passedalong magnetically coded tape 1140, vertical position display 2500calculates and displays the position. While the position is calculatedby display 2500 in the present embodiment, it may alternatively becalculated within sensor 2550 or otherwise calculated. Vertical positiondisplay 2550 provides the operator with a digital readout of the load'svertical position. A suitable system of the display 2500, sensor 2550and tape 1140 is provided by ELGO Electric GmbH, Rielasingen, Germanyunder the product identifier “Z-17 Series” battery powered lengthmeasuring system. The height indicator is not limited to the specificembodiment described herein and may be implemented with any suitablelinear position sensing and display apparatus.

It is furthermore anticipated that equivalent sensor/display apparatusmay be adapted to provide read-outs of the postions of other axes,including for example: the in-out position of column 1000 with respectto base 6000, the horizontal position of main arm 5000 with respect tovertical carriage 2000, and the angle of roll rotation of roll unit5800. Adaptation of the technique to such axes should be straightforwardfor one of ordinary skill in the art.

With reference to FIGS. 19-21, vertical carriage 2000 includes verticallock unit 2225 configured to lock the vertical position of verticalcarriage 2000 upon actuation thereof. Mounting block 2228 on the frontface of vertical carriage 2000 supports handle 2226 for pivotal motionbetween a locked position and an unlocked position. Handle 2226terminates in cam surface 2227 having a radially extending portion 2227a and a radially blunted portion 2227 b approximately 180° therefrom.When handle 2226 is in the locked position shown in FIGS. 19 and 21,radially extending portion 2227 a of cam surface 2227 engages lock shaft2232 and forces shaft 2232 axially toward linear rail 1150. With lockshaft 2232 moved axially toward linear rail 1150, vertical foot pad 2230at the end thereof engages linear rail 1150 and causes a frictional locktherewith. When handle 2226 is rotated 180°, radially blunted portion2227 b aligns with lock shaft 2232 and the axial load is removed fromvertical foot pad 2230 and the brake is released. Foot pad 2230 may bespring loaded so that it automatically retracts when the lock isreleased. FIG. 20 illustrates a through hole 2229 which may be utilizedas an alternative location for vertical lock unit 2225. As shown in FIG.19, cover 2228 is preferably positioned over through hole 2229 when notin use.

Because the load is normally balanced, a friction lock is generallysufficient to hold it in position. As described below, a service lock isalso provided for special service or maintenance situations when theload may be unbalanced.

With reference to FIGS. 19, 20 and 22, safety service lock 2250 will bedescribed. Safety service lock 2250 is provided to secure the load at aparticular service vertical height when being serviced. Service oftenfrequently involves changing the weight of the test head, which can putthe system undesirably out of balance. It is desirable to maintain thevertical position securely while the system is unbalanced. It is furtherdesirable to make sure the load remains vertically locked until balanceis restored by appropriately adjusting the weight of the counterweights.

Referring to FIG. 22, an embodiment of safety service lock 2250 isshown. Safety service lock 2250 includes tang 2255 which is slidablypositioned within groove 2259 defined by opposed lock blocks 2257 and2258. Screws 2249 or the like secure the two lock blocks 2257, 2258together. One end of tang 2255 terminates in operator handle 2252 andthe other end terminates in opposed hooks 2256 a, b. A pair of spacedapart position holes 2264 and 2265 extend through tang 2255 proximate tothe handle end thereof. A threaded hole 2261 a, 2261 b is provided ineach lock block 2257, 2258, respectively, and is configured tothreadably receive screw 2260. In operation, screw 2260 will bepositioned in only one of the holes 2261 a, b; however, screw 2260 maybe used in either block 2257, 2258, whichever is most convenient. Screw2260 includes a threaded portion 2263 configured to engage a desiredthreaded hole 2261 a, b and a tip portion 2262 configured to engage adesired position hole 2264, 2265. FIG. 20 illustrates a through hole2254 which may be utilized as an alternative location for service safetylock 2250. As shown in FIG. 19, cover 2253 is preferably positioned overthrough hole 2254 when not in use.

Service safety lock 2250 extends through vertical carriage 2000 and isconfigured to interact with slot 1135 in column body 1010. The serviceposition is where tang 2255 of lock 2250 is at a height that is alignedwith slot 1135. The service position may easily be found and maneuveredto by an operator with the assistance of the precise position indicatordescribed above. In normal operation (unlocked condition) as illustratedin FIGS. 23 and 24, tang 2255 is held in a retracted position by screwtip 2262 engaging position hole 2265. To lock vertical carriage 2000 atthe service position, screw 2260 may be unscrewed by rotating itsattached knob, thus retracting tip 2262. Tang 2255 may then be insertedinto slot 1135 by pushing on handle 2252 such that tang 2255 projectsfrom blocks 2257 and 2258, as illustrated in FIGS. 25 and 26. Screw 2260may then be retightened such that tip 2262 engages position hole 2264.If the system becomes unbalanced when in the locked service position,vertical carriage 2000 moves slightly, upwards or downwards, dependingupon the direction of the imbalance. The interaction of tang 2255 withslot 1135 prevents motion of more than a few millimeters, and eitherhook 2256 a or hook 2256 b will become hooked behind the slot 1135. Inthis condition, it is not possible to retract tang 2255. This preventsany sudden and potentially large motions of the load if it becomesunbalanced in the locked service position. Further, tang 2255 can not bewithdrawn from slot 1135 by pulling on handle 2252 until the load hasbecome properly balanced or rebalanced. Also, the service position maybe designed into an individual system for a specific application byappropriately locating slot 1135. Additionally, a system could have anumber of service positions by incorporating a number of slots 1135.

As shown in FIG. 19, the front surface of vertical carriage 2000includes a pair of spaced apart horizontal linear rails 2150 withhorizontal lock rail 2175 therebetween. Horizontal linear rails 2150 areconfigured to support main arm plate 5100 of arm assembly 5000. Stopblocks 2180 are positioned on vertical carriage 2000 to limit thehorizontal range of motion of main arm plate 5100.

FIGS. 27 and 28 illustrate the components of arm assembly 5000. Armassembly 5000 generally comprises main arm plate 5100, upper armassembly 5300 and roll gear box assembly 5800. Bearing block 5200extends from the front surface of main arm plate 5100 and pivotallysupports pivot axel 5210. Pivot axel 5210 has an upper portion 5210 aand a lower portion 5210 b. Pivot axel 5210 is configured to pivotallysupport upper arm assembly 5300 and defines a first vertical pivot axisfor arm assembly 5000. Roll gear box assembly 5800 includes bearingblock 5900 that pivotally supports pivot axel 5910. Pivot axel 5910 hasan upper portion 5210 a and a lower portion 5210 b. Pivot axel 5910 isconfigured to be pivotally supported by upper arm assembly 5300 anddefines a second vertical pivot axis for arm assembly 5000.

Referring to FIGS. 29 and 30, main arm plate 5100 will be described inmore detail. Main arm plate 5100 includes linear bearings 5150 a,b,c andd. Linear bearings 5150 a and b are arranged so as to engage one of thelinear rails 2150 and linear bearings 5150 c and d are arranged so as toengage the other linear rail 2150 such that main arm plate 5100 maytranslate horizontally with very little friction along a horizontal axisdefined by linear rails 2150. Stop block 5120 on the rear surface ofmain arm plate 5100 is configured to engage stop blocks 2180 on verticalcarriage 2000. Horizontal lock unit 5125 extends through main arm plate5100 to facilitate locking of the horizontal position of main arm plate5100. Horizontal lock unit 5125 is substantially the same as lock unit2225 and includes handle 5126 with cam surface 5127. Handle 5126 pivotsbetween locked and unlocked positions such that horizontal lock pad 5130is engaged or disengaged from horizontal lock rail 2175. FIG. 30illustrates a through hole 5129 which may be utilized as an alternativelocation for horizontal lock unit 5150. As shown in FIG. 29, cover 5128is preferably positioned over through hole 5129 when not in use.

Upper arm assembly 5300 will be described with reference to FIGS. 31-34.Upper arm assembly 5300 includes I-shaped upper arm block 5310. Lowerbearing 5315 a and upper bearing 5320 a (see FIG. 33) are defined on oneside of upper arm block 5310 and are configured to pivotally support thelower portion 5210 b and upper portion 5210 a, respectively, of pivotaxel 5210. The opposite side of upper arm block 5310 includes lowerbearing 5315 b and upper bearing 5320 b (see FIG. 33) configured topivotally support lower portion 5910 b and upper portion 5910 a,respectively, of pivot axel 5910 of roll gear box assembly 5800.

A lock assembly 5400 is positioned in each half of upper arm block 5310and is configured to rotationally lock the position of the associatedpivot axel 5210 or 5910. The lock assemblies 5400 are preferablysymmetrical and are numbered the same herein. As shown in FIG. 32, eachlock assembly 5400 includes connector rod 5420 extending through arespective hole 5335 in cover 5330 between upper handle 5410 a and lowerhandle 5410 b. Connector rod 5420 is keyed to both handles 5410 a,b andtherefore will rotate with rotation of either handle 5410 a,b. Only asingle handle may be provided, however, having two handles 5410 a,bprovides greater user accessibility depending on the height of the armassembly 5000.

Referring to FIGS. 33 and 34, the upper end of each connector rod 5420is keyed to a respective eccentric member 5440. Eccentric members 5440are configured to rotate eccentrically about the axis of connector rod5420. A respective clamping arm 5430 is positioned adjacent to eacheccentric member 5440. Each clamping arm 5430 includes fixed leg 5432,moveable leg 5434 and u-shaped portion 5436 joining legs 5432 and 5434.Clamping aperture 5438 is defined by legs 5432 and 5434 and u-shapedportion 5436 and is configured to receive an upper portion of arespective pivot axel 5210, 5910. The diameter of clamping aperture 5438varies based on the relative position of moveable leg 5434 to fixed leg5432. If moveable leg 5434 is spaced sufficiently from fixed leg 5432,clamping aperture 5438 will have a diameter greater than the diameter ofthe respective pivot axel 5210, 5910 and the pivot axel 5210, 5910 willbe free to pivot. As moveable leg 5434 is moved closer to fixed leg5432, the diameter of clamping aperture 5438 will be reduced. Uponsufficient movement, the diameter of clamping aperture 5438 will bereduced to an extent such that clamping aperture 5438 clamps on therespective pivot axel 5210, 5910 and prevents pivoting thereof.

Referring to FIG. 34, an initial, unlocked position of clamping arm 5430is defined by a preload adjustment screw 5450 extending through apreload block 5452. Preload adjustment screw 5450 is tightened to movemoveable leg 5434 closer to fixed leg 5432 and loosened to separatethem. By adjusting preload adjustment screw 5450, an initial diameter ofclamping aperture 5438 may be set to a dimension which allows therespective pivot axel 5210, 5910 to pivot with a desired amount ofresistance. A bearing screw 5460 extends from a side of moveable leg5434 and is engaged by eccentric member 5440. After preload adjustmentscrew 5450 is set and with eccentric member 5440 in an unlockedposition, bearing screw 5460 is adjusted such that it head bears againsteccentric member 5440. The unlocked position of clamping mechanism 5400is thereby set. To lock clamping mechanism 5400, either handle 5410 a,bis rotated such that connector rod 5420 rotates and causes eccentricmember 5440 to rotate therewith. As eccentric member 5440 rotates to alocked position, it pushes on bearing screw 5460 and forces moveable leg5434 toward fixed leg 5432, thereby reducing the dimension of clampingaperture 5438 until clamping arm 5430 clamps unto the respective pivotaxel 5210, 5910. To unlock clamping mechanism 5400, either handle 5410a,b is rotated the opposite direction such that eccentric member 5440rotates to its unlocked position. Preferably a compression spring (notshown) is provided between legs 5432 and 5434 to bias moveable leg 5434to the unlocked position. A spring hole 5470 and a spring retaining pin5472 are illustrated in FIG. 34. A corresponding clamping arm may also,or alternatively, be positioned in the lower portion of upper arm block5310 to engage the lower portion of the pivot axel.

Roll gear box assembly 5800 will be further described with respect toFIGS. 35 and 36. As explained above, pivot axel 5910 is pivotallysupported by upper arm assembly 5300. Pivot block 5900 extends fromhousing 5810. Housing 5810 has a generally open through passage 5820configured to receive roll shaft 5830. Roll shaft 5830 supports coupling5832 at one end and includes key 5834 at its opposite end configured tomate with key slot 5844 in roll gear 5840. Coupling 5832 is configuredto support cradle 3000 (see FIG. 1) and is supported with shaft 5830 forrotation about the axis of roll shaft 5830.

Referring to FIG. 36, roll gear 5840 is supported in housing 5810 and isalso supported with shaft 5830 for rotation about the axis of roll shaft5830. Roll gear 5840 engages a vertically extending worm gear 5850. Wormgear 5850 is slidingly mounted to a central axle 5852. One end of axle5852 terminates in bevel gear unit 5856 which engages bevel gear unit5866 attached to wheel shaft 5860 which is supported perpendicular tocentral axle 5852. The opposite end of wheel shaft 5860 includes a wheel5862. Rotation of wheel 5862 rotates wheel shaft 5860 which in turnrotates central axle 5854 via engagement of bevel gear units 5856 and5866. Rotation of central axle 5854 causes worm gear 5850 to rotatewhich in turn rotates roll gear 5840. As such, wheel 5862 may be used toroll cradle 3000 attached to coupling 5832. Alternatively oradditionally, motor 5870 may be attached to central axle 5852 toautomate roll motion control.

In the present embodiment, Bellville washers 5854 at each end of theworm gear 5850 locate it within housing 5810. Bellville washers 5854 actas compression springs such that the load coupled to roll shaft 5830 maybe rotated a few degrees (plus or minus) by an external force. Bellvillewashers 5854 allow this motion, but then exert a counter force to pushthe load back to the neutral position when the external force isreleased. Thus, roll compliance and resilience are provided.

The illustrated cradle 3000 is described in U.S. Provisional PatentApplication 60/916,380 which is incorporated herein by reference. Cradle3000 provides approximately plus or minus 90 degrees of driven tumblemotion including approximately five degrees of compliance. Cradle 3000also provides a few millimeters of linear compliance parallel to thecradle arms. Cradle 3000 further provides approximately plus or minus2.5 degrees of rotational compliance about an axis which is orthogonalto the plane defined by the cradle arms. The illustrated cradle 3000 isan exemplary cradle and the invention is not limited to such. Cradle3000 can have various configurations and is not limited to theconfiguration illustrated herein.

Referring to FIGS. 37-41, a manipulator system 10′ that is analternative embodiment of the invention will be described. Manipulatorsystem 10′ is substantially the same as the previously describedmanipulator system 10, but further includes cable support apparatus7000. For simplicity, manipulator system 10′ is illustrated in FIGS.37-40 without the cradle, the test head, the tester cabinet, andinterconnecting cables.

Referring to FIGS. 37-39, tethers 8610 and 8615 are provided withappropriate coupling gear 8611 and 8616, such as slings or elasticcords, to support electrical wiring cables and coolant tubing or ductswhich are coupled to the test head. Tethers 8610 and 8615 extend fromboom 7650, which is rotatably coupled to the top 1162 of column 1100 bymeans of swivel coupling 8640. Thus, boom 7650 may pivot about avertical axis extending through column 1100. Accordingly, as the testhead is moved through its motion envelope, boom 7650 may rotate with itin order to maintain a near constant distance between the points ofsupport for the cables and the test head.

In some applications, mere rotation of boom 7650 is not sufficient foreffective cable control. It may also be desirable to provide verticalmotion to the points of cable support. For example, it has been foundthat the amount and direction of vertical cable support motion that isdesirable is dependent upon many factors including the size andresiliency of the cable itself, the motions required in day-to-dayoperation, the positions of the peripherals to be docked to, and othersite specific factors. In some instances it may be desirable for thecable support points to move in the same direction as the test head. Inother instances it has been found that moving the cable support in theopposite direction as the test head is beneficial, as this tends to keepthe cable straight. In either case, there may be circumstances where itis desirable that the cable support points move the same distance as thetest head. In other circumstances it may be desirable that the cablesupport points move a fraction of the distance that the test head moves.

Although manipulator system 10′ is illustrated with two supports, it maybe desirable to bundle two or more cable entities into a single cableentity. For example, a coolant tube and an air ducts might be bundledtogether into a single entity. For a given class of test system, suchbundling could be different from one user site to the next. Thus, asystem, which provides the flexibility of having a variable number ofsupports is desirable.

The present exemplary embodiment shown in FIGS. 37-39 provides twotethers 8610 and 8615 as supports. Tethers 8610 and 8615 are configuredso that as the test head moves vertically, the supports also movevertically in the same direction and at the same rate (and thus the samedistance) as the test head. Thus, for example, if the test head israised one meter, the tethers 8610 and 8615 are also raised one meter.

In the exemplary embodiment of the present invention as illustrated inFIGS. 37-39, tethers 8610 and 8615 are routed, through appropriateopenings, up into boom 7650 where they encounter pulleys which directthem along boom 7650 towards swivel coupling 8640. Tethers 8610 and 8615are then directed downwards into column 1100 where they are routed andterminated to produce the desired motion effect.

FIG. 40 provides a schematic illustration of the above. Two cableentities 8611 and 8616 are supported by tethers 8610 and 8615,respectively. Tethers 8610 and 8615 pass through respective openings8614 and 8619 in the bottom of boom 7650 and then engage respectivepulleys 8613 and 8618. Thus, tethers 8610 and 8615 are directedgenerally horizontally along boom 7650 towards column 1100. In thepresent exemplary embodiment, requirements can be satisfied by havingboth tethers behave in the same fashion. Thus, both tethers 8610 and8615 move in unison; and both simultaneously engage single pulley 8630,which directs them downwards through swivel coupling 8640 into column1100. Because, pulley 8630 is located approximately directly aboveswivel coupling 8640, boom 7650 may pivot approximately 90 degrees ormore about swivel coupling 8640 without undue resistance from tethers8610 and 8615 and without adversely effecting tethers 8610 and 8615.

If tethers 8610 and 8615 are made of a material that is round in crosssection, such as rope, pulley 8630 may be one of a style that allowstethers 8610 and 8615 to ride it side-by-side (perhaps each having itsown groove to prevent harmful over rides). However, in a preferredversion of this exemplary embodiment, tethers 8610 and 8615 are made ofa flat, woven strapping. In this case pulley 8630 may have a flatsurface and tethers 8610 and 8615 may round pulley 8630 stacked one ontop of another. If the diameter of pulley 8630 is relatively large incomparison to the thickness of the strapping, any slippage betweenadjacent straps will be minimal.

While two tethers are described and illustrated herein, any number oftethers may be accommodated, for example from just one to as many asfour or more. Thus, a system may be designed and manufactured so that itcan be adapted to handle any reasonable number of tethers according toapplication and situational needs that are not known a priori. In FIG.38, for example, a number of pulley mounting points 7652 are shown,which enable a variable number of pulleys and pulley locations, enablingthe system to be adapted to different situations and changing needs.

In FIG. 39, which is a detailed rear view of column 1100 with the reardoor removed, it is seen that tethers 8610 and 8615 are directeddownwards and are fastened to an eyebolt attached to the upper surfaceof the counterweight assembly 1500. Thus, the test head load, thecounterweights and the tethers will all move vertically as a singleunit. The situation is illustrated schematically for a single tether,say tether 8610, in FIG. 41.

In FIG. 41, a LOAD is supported by vertical carriage 2000′ that may movevertically along column 1100′. Carriage 2000′ is supported by loadcarrying straps 1300′ that are coupled to the COUNTERWEIGHTS. Straps1300′ are passed over respective pulleys 1120′ and 1124′ near the top ofcolumn 1100, reversing their direction in traveling from the LOAD to theCOUNTERWEIGHTS. Thus, as the LOAD moves upwards, the COUNTERWEIGHTS movedownwards and vice versa. The illustrated CABLE is supported by tether8610′. Although not shown, the CABLE may be assumed to be coupled to theLOAD. Tether 8610′ passes over pulleys 8623′ and 8630′ within boom 7650′and is finally attached to the COUNTERWEIGHTS. Thus, for example, as theLOAD is moved up a distance X, the COUNTERWEIGHTS move down the samedistance X, causing the CABLE to be raised the distance X. Accordingly,this arrangement causes the CABLE support to be moved in the samedirection and the same distance as the test head as desired.

While exemplary embodiments of the invention have been shown anddescribed herein, it will be understood that such embodiments areprovided by way of example only. Numerous variations, changes andsubstitutions will occur to those skilled in the art without departingfrom the spirit of the invention. Examples of such variations areincluded below.

The positioner system is not limited to electronic device testingequipment, as other applications and industries are envisioned. Thepositioner system may be utilized in X-Ray machines, or any otherautomated load bearing equipment. Accordingly, the term “load” recitedin the appended claims is not limited to a test head, and may representany object. Also, the positioner system is not limited toelectrically-powered motors or actuators, as other power systems areenvisioned such as pneumatic, air-powered pneumatics, hydraulics,motors, gears, internal combustion, etc.

Accordingly, it is intended that the appended claims cover all suchvariations as fall within the spirit and scope of the invention.

What is claimed is:
 1. A manipulator for positioning a load, saidmanipulator comprising: a support member configured to move the loadalong a given path; a marker provided along the given path; a sensorassociated with the support member and configured to sense a positionalong the marker; and a position display unit configured to receive aposition signal from the sensor and display a current position of thesupport member.
 2. The manipulator of claim 1 wherein the given path isa linear path.
 3. The manipulator of claim 1 wherein the given path is acircular path.
 4. The manipulator of claim 1 wherein the marker includesa magnetically coded tape and the sensor includes a magnetic sensor. 5.The manipulator of claim 1 wherein the position display unit provides adigital readout of the current position of the support member.
 6. Themanipulator of claim 1 wherein the position display unit provides amechanical readout of the current position of the support member.
 7. Amanipulator for positioning a load according to claim 1, the manipulatorfurther comprising: a base unit including a toothed rail; and a columnconfigured to support the load, the support member moves aloe thecolumn, the column moveably supported on the base unit and including arotative actuator that drives a gear along the toothed rail to effectmovement along the base unit.
 8. The manipulator of claim 7 wherein atleast one linear rail is positioned along the base unit parallel to thetoothed rail and a corresponding linear bearing is positioned on thecolumn and configured to move axially along the linear rail.
 9. Themanipulator of claim 7 further comprising a clutch mechanism such thatthe rotative actuator may be disengaged such that the column is moveablerelative to the base unit independent of the rotative actuator.
 10. Themanipulator of claim 7 wherein the rotative actuator is configured tolock the position of the column relative to the base unit when therotative actuator is not actuated.
 11. The manipulator of claim 7wherein the rotative actuator is an electric motor.
 12. A manipulatorfor positioning a load according to claim 1, said manipulator furthercomprising: a column assembly; the support member supported by thecolumn assembly; at least one strap extending over a strap pulley andconnecting the support member to a counterweight assembly such that thesupport member and the load are substantially balanced by thecounterweight assembly; and a motor configured to drive the strap pulleysuch that the support member is moved along the given path.
 13. Themanipulator of claim 12 wherein the motor includes an output pulleyoperably connected with the strap pulley.
 14. The manipulator of claim13 wherein a belt extends between the output pulley and an intermediatepulley supported on a common shaft with the strap pulley.
 15. Themanipulator of claim 12 further comprising a clutch mechanism such thatthe motor may be disengaged such that the carriage is moveable along thegiven path independent of the motor.